Whay does my peach tree grow small fruit? The peaches are golf ball size.
My Peach Tree Only Grows Peaches Golf Ball Size
Certified GKH Gardening Expert
This sounds like a chilling issue. If a peach tree gets just a little bit too little chilling in the winter, it will button the fruit, which means that it tries to grow them, but they will be deformed and fail to mature. I would check that the variety is appropriate for your area in terms of chilling. Here is more information on chilling: https://www.gardeningknowhow.com/edible/fruits/peach/peach-chill-hours.htm
Too much fruit production can also lead to stunted peaches. Thinning can alleviate this: https://www.gardeningknowhow.com/edible/fruits/peach/peach-tree-thinning.htm
Another possibility is that there is a problem with pollination. If this is the case though, the tree will drop the fruit in late spring or early summer. If you suspect a pollination problem, these articles will help: